Global warning causes catastrophes and changes in ecosystems. Hence, much attention is paid to so-called green industries focused on low consumption and high efficiency. A lot of effort is made to develop light-emitting diodes because they are small in size, long in life and quick in response, produce a little heat, consume a little energy and do not include mercury. Most of the effort is made to improve the efficiency of the light-emitting diodes.
Conventionally, light-emitting diodes are connected to one another in parallel or serial, thus forming an array. The array is connected to a power supply so that each light-emitting diode therein emits light. If the illumination is not enough, more light-emitting diodes care connected to one another in parallel or serial, thus forming another array. The additional array is connected to an additional power supply.
As discussed above, each array is connected to a power supply, i.e., two power supplies are used for two arrays. To double the illumination, the consumption of energy must be doubled.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.